Container with mixing device



June 22, 1965 A. H. KOEPF CONTAINER WITH MIXING DEVICE 2 Sheets-Sheet 1 Filed Oct. 23. 1961 HOT I"Il

IN V EN TOR.

ALMONT H. KOEPF ATTORNEY June 22, 1965 A. H. KOEPF 3,190,284

CONTAINER WITH MIXING DEVICE Filed Oct. 25. 1961 2 Sheets-Sheet 2 FIG. 3

b fl

FMMMMMQS OUTLET TEMPERATURE "F TANK WATER 180%. 2 cow WATER INLET 60F.

z a 4 e DRAWN WATER FLOW- INVENTOR.

Gals. per min. ALMONT H. KOEPF FIG. 4 B

ATTORNEY tures of hot water storage tanks practical.

a corporation of Delaware Filed Oct. 23, 1961, Ser. No. 146,948 11 Claims. (Cl. 126362) This invention relates to a system for storing and handling fluids at elevated temperatures. More particularly, it relates to a unique system for storing and handling water at elevated temperatures, as well as certain unique components of such a system, wherein a unique arrangement is employed for storing hot water in an aluminum storage unit and for mixing or blending the hot water drawn from the storage unit with cooler Water prior to use of the drawn water.

Accordingly, it is a primary purpose of this invention to provide a unique system, as well as unique components usable therein, for storing and handling water at elevated temperatures wherein a unique arrangement is employed for storing hot water in an aluminum storage unit and for mixing or blending the hot water drawn from the storage unit with a cooler water prior to use of the drawn water.

Other purposes and advantages of the instant invention will be more readily understood from a review of the following detailed description, when taken in conjunction with the accompanying drawings, throughout which like reference characters indicate like parts and wherein:

FIG. 1 is an elevational sectional view of a fluid mixing or blending device for use in practicing the instant invention;

FIG. 2 is a horizontal sectional view of the mixing device shown in FIG. 1, taken along the line 22 thereof and with parts removed for the sake of clarity;

FIG. 3 is a vertical sectional view of a typical hot water storage tank that may be used in practicing the instant invention; and

FIG. 4 is a graph illustrating the performance characteristics of a water storage unit provided with the mixing device of FIGS. 1 and 2.

In providing fluid at elevated temperatures, such as in the case of domestic hot water units, there has been considerable interest in the use of aluminum as the structural material for the hot water storage tanks. One of the major problems encountered in the use of aluminum hot water storage tanks concerns corrosion. The cor ,rosion rate of aluminum exposed to Water at elevated temperatures normally increases as the temperature of the Water is increased from ambient temperature up to approximately 150 F. Then as the temperature increases from between 150 to 200 F, the corrosion rate decreases markedly. This phenomenon is explained by the structure of the diflerent oxide films that form on the metal surfaces at temperatures above 150 F. and below 150 F. At water temperatures below 150 F., the oxide film is relatively thick, porous, and permeable and in the form of a tri-hydrate aluminum oxide, namely Al O .3H O. This tri-hydrate oxide film has only moderately good resistance to corrosion and cannot be relied on to provide the necessary corrosion-resistant film required to make the use of aluminum in the wall struc- Moreover, water heaters in normal residential use normally require water to be dispensed at temperatuers of approximately 140 F.

As noted above, it has been found, rather surprisingly, that as the temperature of the water in an aluminum-walled storage tank increases from approximately 150 F. to about 200 F., the corrosion rate of the aluminum decreases markedly. This is due to the I United States Patent 3,190,284 Patented June 22, 1965 "ice formation of an oxide film on the water-exposed aluminum surfaces, which is thin, adherent and relatively impermeable and it is known as boehmite. Boehmite is a mono-hydrate oxide in the so-called gamma crystalline modification and has the formula Al O .H O. It is extremely resistant to corrosive attack, although it is not particularly stable at low temperatures at which transformaion to the aforesaid tri-hydrate oxide occurs in time. However, in the case of the normal thermostatically controlled residential and commercial water heaters used today, the time periods involved in the cooling and reheating cycles are so negligible that once established the oxide film formed on an aluminum water heater wall will for all practical purposes remain in its corrosion-resistant boehmite form.

From the above, it will be readily appreciated that the optimum storage temperature for water in an aluminumwalled hot water tank is above 150 F. A gradient of oxide film quality exists between 150 F. and 200 F. and it has been found in the case of most water that is commercially or domestically available that a temperature of approximately 180 F., produces the optimum gradient of film for all practical purposes. This temperature, on the other hand, is usually above the dispensing temperature desired for residential water systems because it is so hot that there is danger of burning the skin of persons with whom it comes in contact.

The problem of supplying hot water at the optimum temperature of about F. while using the advantageous characteristics of a boehmite oxide film has been has been overcome by use of the novel mixing valve device of the instant invention wherein water at ambient temperature, normally between approximately 35 F. and 70 F, and referred to hereinafter as cold water, is mixed with water as it is drawn from the storage tank at tempera tures above F. When this mixing or blending of hot and cold Water takes place, the final or outlet temperature of the drawn water is betweena desirable l20-150 F. and for all practical purposes in the neighborhood of 140 F. By use of the novel mixingvalve device of the instant invention, it is possible to provide dispensed water at the desired consumption temperature, while still taking full advantage of the boehmite film "formation needed to prolong the life of the aluminum- Walled Water storage tank by maintaining water temperatures in the desirable range of 150 F. to 200 F. and preferably at 180 F. in the storage tank. It is to be further observed that in water heater storage tanks made of materials other than aluminum, an increase in temperature above 150 F. normally causes rapid deterioration to occur. Galvanized steel, for example, is subjected to a galvanic potential reversal at these elevated temperatures. The steel becomes anodic to the zinc and rapid oxidation and deterioration of thesteel results. Glass-lined steel is subject to rapid deterioration of the glass coating by thermal cracking at these elevated temperatures and with water of certain compositions, the glass material actually dissolves.

With further reference to the drawings, and in particular FIGS. 1-3, the novel mixing valve device 11 which is advantageously used in the instant invention can be mounted on the top of storage tank, such as the aluminum-walled storage tank A shown in FIG. 3. Tank A is comprised of side wall a, bottom 12 and top c. The mixing valve device acts to maintain the temperature of the water drawn from the tank A through conduit B at substantially a constant temperature of approximately 140 F. regardless of the rate of tiow by mixing or blending the water withdrawn from tank A with the cold water from cold water conduit C. I

The mixing device 11 includes a mixing block 13 provided with a mixing or blending tube 15 disposed within the across the chamber 17 of the block 13. Chamber 17' 15 has an orifice 19 for introducing cold water flOIl'l' conduit C into the bore 15 of the mixing tube 15 as the water is drawn from the storage tank A in 'a manner to be morefull described hereinafter.

As indicated in the drawings, block 13 is also advantageously provided with a valve chamber 21. Chamber 21 is in open communcation with the interior or bore 15' of mixing tube 15 through the medium ofoutlet 23 and withthe interior of tank A through the medium of inlet- 24 provided with the ball check valve 25] Theball' 27,

of valve25 is adapted to seat by gravity upon the seat. 1

flow and with the orifice 19,-outlet 23 and inlet 24 being of appropriate sizes, that the ball 27 is suitably displaced wateris drawn from tank A from the seat or'seating portion 29 bythe flow of'hot' water entering the valve chamber 21 from the storage tank as the cold water enters pipe C, and that at the same time theoutlet temperature of the drawn hot tank water,

such as a hydrolysis resistant nylon or high temperature resistant polypropylene compound. Block 13 can be made of a suitable aluminum alloy while the ball 27 can be made completely of aluminum, or a suitable plastic material, or it can have a metal core coated with a suitable rubber or plastic' material. Internally and externally threaded bushingsor seals 37 and 39 can be used if desired to sealthe pipes or conducits C and 33 to V the block 13." One end of tube 15 abuts against seal39 and the other end of tube 15 abuts against the shoulder 23 of block; 13 adajacent outlet 23. The use of removable plug 35 atone end of the valve chamber 21 also makes it easy to repair or clean valve assembly '25. Bottom surface 35' of plug 35 is so positioned during assembly that at high flow rates ball 27 will not seat itself in opening or outlet 23 and'thereby cutofi supply of hot water to mixing tube 15. j

In some instances, it may be desirable to use an oversized valve chamber 21, such that comparatively high velocities can bedeveloped when; the valve' is opened "fully. The ball 27 will then be'violently agitated and collide with the walls of the valve chamber 21, thereby loosening and removing undesirable deposits which tend to form on the walls of thevalve chamber 21.

The advantageous operating characteristics of the mixing device of the instant invention is illustrated in the graph of FIG. 4., At. flow rates of the water drawn from outlet pipe 33 of between -0 to about of a gallon per minute thetemperature gradient of the water ranges between 120 F. to roughly 150 F., asindicated by curve segment Z. At steady flow rates of about of a gallon water becomes low (for example less than about 0.1 pound per squire inch), the passage or entrance of cold i water through the orifice 19 is usually blocked and the mixted outletterneprature of the drawn Water in outlet element 33 approaches the temperature of the tank which,

at 180 B, would be entirely too hot for ordinary usage.

It would appear that one of the reasons for this is because the lighter hot water attempts .to rise and counter the elforts of the heavier cold Water to fall and enter the mixing tube 15 through the relatively smallorifice or inlet 19.. Thus, a stratification occurs and the cold water is prevented from entering the mixing tube or chamber 15. This in turn means that the mixing device would become a hazard at low flow rates and the hot water dis- 4 charged at these low flow rates could easily burn the skin of a person using the hot water.

If a check valve is incorporatedin the mixing or blending device 11, these temperature characeristics are markedly improved. If a ball 27, such as that shown in FIG. 1, is used with an ungrooved seating portion, the

temperature at the low flow rates is not hot enough to I be dangerous and, in fact, tends to fall below the desirable 140 F. because the ball 27 will tend to shut' oif the flow of the hot water from the tank at the low rates. In view of the afeoresaid problems, it has been found that it ispreferableto use additional inlet means or by-pass grooves in the seat 29, such as the grooves 31 shown in FIGS. 1 and 2. These grooves 31 allow' a suitable amount of hot water even at low flow rates to by-pass valve 25 without completely blocking the inflow of the cold water through the orifice 19.'

In order, to maintain the mixed or blended cold and hot water drawn through outlet element or pipe 33 at the normal desired temperature of 140 F. while at the same time maintaining hot water temperature in the tank at approximately 180 F. and with the cold water entering pipe C being at ambienttemperature of normally be tween 35 F. and 70 v F., it has been found that'the ratio a minute, the temperature gradient of the drawn water is again between Rand- F., as indicated by curvesegment At flow rates above /1 of a gallon'per minute'the temperatureof the drawn water is maintained at a constant optimum 140 F. temperature, as indicated by curve segment X. Thus, for all practical purposes, it can be said that in the normal use of the mixing de vice where the drawnwater will, in most instances, exc'eed the of agallon per minute flow rate, a substantially constant 140 F. temeprature will be effectively maintained.

A further advantageous feature of the'instant invention resides in the fact that due to the rise in the water temperature in the'storage tank from the normal 140 F. to approximately F., the 'elfective hot water availability of the heater system isinc reasedby approxi mately 50%. This is accomplished as a result of blendingtwo units of hot-water with one unit of cold water in the mixing tube15.: Thus, the discharge of water at a temperature of approximately 140 F; isatleast 50% greater in quantity than the 140 F. water produced by normal hot water heater of comparable size. In addition, the heat input from natural gas firing unit 45 to the storage tank'A can be similarly increased by at least 50% because of the superior thermal properties of the aluminum alloys used in tank A in comparison with the prior art steel stonage tanks. The size of the burner unit 45 may be increased and the combusion passages may be adalloys containing at leastf50% aluminum by weight.

It is to be further noted that although the preferred embodiment of the invention contemplates that tankior receptacle A would be made completely of aluminum, there may be instances where it would have made of a composite stock material, suchias aluminum bonded to other materials, either metallic or non-metallic, and with the aluminum surface portions of the composite stock material always being exposed to the water in tank A.

An advantageous embodiment of the invention has been shown and described. It will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope thereof as set forth in the appended claims, wherein what is claimed is:

1. Apparatus for use in providing fluid at a predetermined outlet temperature by mixing fluid of a first temperature below the desired predetermined outlet temperature with fluid of a second temperature above said predetermined outlet temperature, said apparatus comprising in combination a container for receiving and storing the fluid of said second temperature, a mixing device aflixed to said container, said mixing device being provided with a first inlet means in communication with the interior of said container, a second inlet means for the fluid of said first temperature, and a first outlet means and a second outlet means, said mixing device further including a valve means disposed adjacent said first inlet means and a mixing tube interposed between and communicating with said valve means and said first and second outlet means, said mixing tube being provided with an orifice means in open communication with said second inlet means for receiving fluid of said first temperature and for introducing the fluid of said first temperature into said mixing tube where it is adapted to mix with the fluid of the second temperature drawn from said container prior to the time the fluid is finally discharged through said first outlet means, said second outlet means also being interposed between and communicating with said mixing tube and said valve means, the cross-sectional dimension of said second outlet means being at a predetermined ratio to the cross-sectional area of the orifice means of said mixing tube.

2. A device as set forth in claim 1 wherein the valve means comprises a valve member and a valve seat for said valve member with said valve member being normally seated by gravity on said seat, said seat being further provided with groove means operable to allow fluid at said second temperature to by-pass said valve means when said valve means is substantially closed.

3. Apparatus for use in providing fluid of a predetermined outlet temperature by mixing a fluid at a first temperature below said predetermined outlet temperature with a fluid at a second temperature which is above both the predetermined outlet temperature and said first temperature fluid, said apparatus comprising the combination of a storage container for the fluid at said second temperature, a mixing device affixed to said container, said mixing device being provided with a first inlet means for receiving the fluid at the second temperature from said storage container, a second inlet means for receiving the fluid at said first temperature and an outlet means, said mixing device further including a valve means for said I first inlet means, a mixing tube disposed in said second inlet means and intermediate said valve means and said outlet means, said mixing tube also connecting said valve means with said outlet means, said mixing tube being provided with a normally open orifice for placing the interior of said tube in communication with said second inlet means so as to allow the fluid at said first temperature to be mixed with the fluid at said second temperature prior to the discharge of the fluid at said predetermined outlet temperature through said outlet means.

4. A device as set forth in claim 3 wherein said valve means comprises a valve member and a seat for said valve member with said valve member being normally seated by gravity on said seat, said seat being further provided with groove means for allowing the fluid at said second temperature to by-pass said valve means when the valve member is substantially fully seated on said seat.

5. A device as set forth in claim 3 wherein the valve means is provided with an outlet means connecting said valve means with said mixing tube, and wherein the ratio of the cross-sectional area of said last-mentioned outlet means to that of the orifice of said mixing tube is 2: 1.

6. In a water storage and dispensing system the combination of a storage receptacle wherein the surfaces of the receptacle that are exposed to the water consist of a metal selected from the group consisting of aluminum and aluminum alloys, means for heating said receptacle in order to raise and maintain the water in the receptacle above a predetermined elevated temperature so as to promote the formation and maintenance of a highly corrosion-resistant oxide film on the said inner surfaces of the receptacle, said system further including receptacle outlet means for dispensing the water at the said predetermined elevated temperature from the receptacle, receptacle inlet means for supplying fresh water to said receptacle at a temperature below the said predetermined elevated temperature and in quantities substantially equal to the quantities dispensed from and through said receptacle outlet means, a dispensing conduit, a fluid-mixing means interposed between said receptacle outlet means and said dispensing conduit and connecting said outlet means with said dispensing conduit, said mixing means also being connected to and in open communication at all times with said receptacle inlet means, whereby said mixing means can effect a mixing and blending of the water withdrawn from the receptacle at said predetermined elevated temperature through the outlet means and prior to entrance of said water at said predetermined elevated temperature into the dispensing conduit with at least a portion of the lower temperature water that enters the receptacle through said inlet means.

7. A system as set forth in claim 6 wherein the corrosion-resistant oxide film comprises Al O .H O.

8. A system as set forth in claim 6 wherein said receptacle outlet means includes a valve and a valve bypass means operable to pass water from the receptacle through the receptacle outlet means and to said fluidmixing means at low rates of flow of Water from the receptacle.

9. In a water storage and dispensing system, the combination of a storage receptacle wherein the surfaces of i the receptacle that are exposed to said water consist of a metal selected from the group consisting of aluminum and aluminum alloys, means for heating said receptacle and for raising and maintaining the water in the receptacle above F. so as to promote the formation and maintenance of a highly corrosion-resistant oxide film comprising Al O .H O on the said inner surfaces of the receptacle, said system further including receptacle outlet m eans for dispensing the water from the receptacle, a dispensing conduit, a receptacle inlet means for supplying fresh Water to said receptacle at a temperature substantially below 150 F. and in quantities substantially equal to the quantities dispensed from and through said receptacle outlet means, a fluid-mixing means interposed between said receptacle outlet means and said dispensing conduit and interconnecting said receptacle outlet means with said dispensing conduit, said mixing means comprising tube means provided with an orifice in open communication at all times with said receptacle inlet means and with the interior of said tube means whereby said mixing means can effect a mixing and a blending of the water above the 150 F. temperature withdrawn from the receptacle and prior to entrance of the said water above the 150 F. temperature into the dispensing conduit with at least a portion of the lower temperature water that enters the receptacle through said receptacle inlet means.

10. In a water storage and dispensing system as set forth in claim 9 wherein a gravity operated check valve is disposed in said receptacle outlet means.

11. In a water storage and dispensing system' as set forth in claim 9 wherein said receptacle outlet means is provided witha valve seat and a gravity actuated check valve that is adapted to rest on said seat, said seat also being provided with valve by-pass grooves-and the ratio of the cross-sectional area' of the portion of said receptacle outlet means immediately adjacent said tube means to the cross-sectional area of the orifice of the tube means being on the order of 2: 1, whereby water at relatively-low rates and above 150 F. can be withdrawn from' the receptacle and be mixed withthe lower temperature water entering the receptacle inlet means prior to entrance of thewater from receptacle into said dispensing conduit.

References Cited by the Examiner UNITED STATES PATENTS Howell 137-5 19.5 Shnell Q. 137- 335 Williams, 126362 XR Wheeler -L 126362 XR Shields 137513.5 X Watts 137-337 X LaRue 12217 Lyle 137337 X Lyle- 137--337 CARY NELSON, Primary Examiner. 

1. APPARATUS FOR USE IN PROVIDING FLUID AT A PREDETERMINED OUTLET TEMPERATURE BY MIXING FLUID OF A FIRST TEMPERATURE BELOW THE DESIRED PRDETERMINED OUTLET TEMPERATURE WITH FLUID OF A SECOND TEMPERATURE ABOVE SAID PREDETERMINED OUTLET TEMPERATURE, SAID APPARATUS COMPRISING IN COMBINATION A CONTAINER FOR RECEIVING AND STORING THE FLUID OF SAID SECOND TEMPERATURE, A MIXING DEVICE AFFIXED TO SAID CONTAINER, AID MIXING DEVICE BEING PROVIDED WITH A FIRST INLET MEANS IN COMMUNICATION WITH THE INTERIOR OF SAID CONTAINER, A SECOND INLET MEANS FOR THE FLUID OF SAID FIRST TEMPERATURE, AND A FIRST OUTLET MEANS AND A SECOND OUTLET MEANS, SAID MIXING DEVICE FURTHER INCLUDING A VALVE MEANS DISPOSED ADJACENT SAID FIRST INLET MEANS AND A MIXING TUBE INTERPOSED BETWEN AND COMMUNICATING WITH SAID VALVE MEANS AND SAID FIRST AND SECOND OUTLET MEANS, SAID MIXING TUBE BEING PROVIDED WITH AN ORIFICE MEANS IN OPEN COMMUNICATION WITH SAID SECOND INLET MEANS FOR RECEIVING FLUID OF SAID FIRST TEMPERATURE AND FOR INTRODUCING THE FLUID OF SAID FIRST TEMPERATURE INTO SAID MIXING TUBE WHERE IT IS ADAPTED TO MIX WITH THE FLUID OF THE SECOND TEMPERATURE DRAWN FROM SAID CONTAINER PRIOR TO THE TIME THE FLUID IS FINALLY DISCHARGED THROUGH SAID FIRST OUTLET MEANS, SAID SECOND OUTLET MEANS ALSO BEING INTERPOSED BETWEEN AND COMMUNICATING WITH SAID MIXING TUBE AND SAID VALVE MEANS, THE CROSS-SECTIONAL DIMENSION OF SAID SECOND OUTLET MEANS BEING AT A PREDETERMINED RATIO TO THE CROSS-SECTIONAL AREA OF THE ORIFICE MEANS OF SAID MIXING TUBE. 